1. Field
The present application relates generally to the operation of broadcast systems, and more particularly, to methods and apparatus for improved program acquisition for use with MPEG-2 based systems.
2. Background
In a typical broadcast network, content is transmitted to wireless devices in a transport stream. For example, the transport stream may be an MPEG-2 based transport stream. The transport stream utilizes a unique integer value referred to as a packet identifier (PID) to identify elementary streams of transmitted programs.
With regards to MPEG-2 based systems, Program Specific Information (PSI) is utilized that comprises a Program Association Table (PAT) and Program Map Table (PMT). The PAT provides correspondence between program numbers and PID values associated with the corresponding PMTs in the transport stream. The program number is the numeric label associated with a program. The Program Map Table provides the mappings between program numbers and PIDs that identify the program elements that comprise each program. A single instance of such a mapping is referred to as a “program definition”. The PMT is the complete collection of all program definitions for a transport stream. The PAT and PMT are transmitted with a certain periodicity, typically every 100 ms or less. A receiving device needs to capture these tables before program playback in order to identify and locate the program elements that are part of a desired program.
In general, mobile receivers that are capable of receiving MPEG2 transport streams are resource limited. For example, more and more mobile receivers currently available have been designed to receive digital television broadcasts (e.g., DVB-H). However, one common limitation of such receivers is the number of PIDs that can be filtered or processed simultaneously. Due to this limitation, the conventional approach is to start filtering a PMT PID only when the corresponding program needs to be presented (i.e., playback). This introduces time latencies when launching a program or switching between programs since the appropriate PID has to be determined and the associated program components acquired.
Therefore, it is desirable to have a program acquisition mechanism that operates to allow a device to launch and switch between programs in an MPEG-2 transport stream in an efficient manner while minimizing time latencies associated with conventional systems.